Roundup weedkiller instructions

Updated November 21, 2016

Roundup Weed & Grass Killer is a commonly used herbicide for controlling weeds and unwanted grass. The primary ingredient in Roundup is glyphosate. It can be used in vegetable and flower gardens and around trees, fences, driveways and patios. Roundup, when correctly applied, dries within 30 minutes, making the area safe for activity soon after spraying. Roundup is not selective and will kill any plant it contacts, so it is not recommended for use on lawns.

Put on gloves, long trousers, a long-sleeve shirt, closed toe shoes and safety glasses for protection before handling Roundup. Place a garden sprayer on a flat and level surface and remove the screw on top.

Pour Roundup weed killer into a measuring cup. Refer to the manufacturer's directions for the exact ratio of Roundup to water that should be used. As a rule of thumb, 85.1gr. of Roundup are used to 1 gallon of water for many weed killing applications. Fill the spray tank to the desired level in the spray tank and place the lid on the tank securely.

Choose a time to apply the Roundup weed kill solution when the wind is calm to avoid having the chemical drift when spraying. Select a time that there is no rain forecast for several hours and there is no dew or moisture on the weeds to be sprayed.

Pressurise the garden sprayer by releasing the pump handle and pumping up and down into the spray tank. Hold the spray tank in one hand and the applicator wand in the other. Place the tip of the wand within six inches of the weeds to be sprayed.

Spray a small amount of Roundup onto the leaves and stem of the weed. Adjust the spray pattern of the Roundup by turning the tip of the spray wand. Select a fan, stream or mist of Roundup with which to spray the weeds.

Monitor the area sprayed with the Roundup for at least 30 minutes following the application. Keep children and pets clear of the area as the chemical dries.


Spray the weeds when actively growing for good results. Watch for signs of die back in the weeds within 24 hours or so. Apply more Roundup to the weeds after allowing the first application three days to work.

Things You'll Need

  • Roundup
  • Measuring cup
  • Garden sprayer
  • Gloves
  • Safety glasses
  • Long-sleeve shirt and trousers
  • Closed toe shoes
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About the Author

Keith Dooley has a degree in outdoor education and sports management. He has worked as an assistant athletic director, head coach and assistant coach in various sports including football, softball and golf. Dooley has worked for various websites in the past, contributing instructional articles on a wide variety of topics.